Re: Current control of induction motors
Posted: Sun Feb 05, 2023 11:54 am
Just a note on tuning. I just attempted a drive with fslipmin=1
This eliminates the vast majority of the low speed oscillation.
The only negative side-effect are these current spikes that sometimes happen when reducing to 0% throttle. With a minimum slip, the algorithm is forced to reduce the output voltage all the way down to zero to reach zero torque. At some speeds, this seems to create a current spike as some residual energy is discarded. However, this has no impact on driving and don't seem to be large enough to damage anything.
Of course, the V/Hz firmware reduces torque to zero by reducing voltage so I have to imagine these current spikes occur there too. On a mildly related note, this is probably the same issue that makes regen unstable. It's one of those edge cases where reducing voltage *doesn't* reduce current, and my algorithm just doesn't understand that concept.
In any case, this setting is worth trying as it can certainly improve the smoothness of the drive at low speed.
I would also reiterate, if you want to test this code, start with a rather lower value of throtcur and and work your way up.
This eliminates the vast majority of the low speed oscillation.
The only negative side-effect are these current spikes that sometimes happen when reducing to 0% throttle. With a minimum slip, the algorithm is forced to reduce the output voltage all the way down to zero to reach zero torque. At some speeds, this seems to create a current spike as some residual energy is discarded. However, this has no impact on driving and don't seem to be large enough to damage anything.
Of course, the V/Hz firmware reduces torque to zero by reducing voltage so I have to imagine these current spikes occur there too. On a mildly related note, this is probably the same issue that makes regen unstable. It's one of those edge cases where reducing voltage *doesn't* reduce current, and my algorithm just doesn't understand that concept.
In any case, this setting is worth trying as it can certainly improve the smoothness of the drive at low speed.
Code: Select all
fslipweak=4
fslipmax=3
fslipmin=1
throtcur=6.5
curkp=1
ocurlim=900
idcmax=650